Preparation method and application of insulating varnish

Abstract

The invention belongs to the technical field of paint, and discloses a preparation method and application of an insulating paint. The preparation method comprises raw material components A and B; raw material components A comprises: 55-65 parts of epoxy resin, 10-20 parts of modified filler, 1-5 parts of dihydroxy polydimethylsiloxane, 1-10 parts of auxiliary agent, and 30-50 parts of water; raw material components B comprises a curing agent; wherein, the preparation method of the modified filler comprises the following steps: mixing nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, and solvent, and then adding sorbitol for stirring and dispersion to obtain the modified filler. The film layer formed by the insulating paint has both high breakdown strength and good impact resistance, wherein the breakdown strength is not less than 161KV / mm, and the impact resistance is not less than 85cm.

Description

Technical Field

[0001] The invention belongs to the technical field of varnishes, and in particular relates to a preparation method and application of insulating varnish. Background Art

[0002] Insulating varnish is a necessary material for electrical equipment. For example, the surface of a conductive wire often needs to be coated with a layer of insulating varnish to improve the safety of electricity use. This places high demands on the insulation and mechanical properties of the insulating varnish. Specifically, the insulating varnish layer needs to have high breakdown strength and good impact resistance, and further needs to have good water resistance, and maintain high breakdown strength even in rainy environments.

[0003] However, the breakdown strength of existing insulating varnishes under normal conditions is generally difficult to exceed 155KV / mm, and the impact resistance is difficult to exceed 80cm.

[0004] Therefore, there is an urgent need to provide a new insulating varnish which has both high breakdown strength and good impact resistance. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a preparation method and application of an insulating varnish. The film layer formed by the insulating varnish prepared by the preparation method of the present invention has both high breakdown strength and good impact resistance, wherein the breakdown strength is not less than 161KV / mm, and the impact resistance is not less than 85cm.

[0006] A first aspect of the present invention provides a method for preparing an insulating varnish.

[0007] Specifically, a method for preparing an insulating varnish includes a raw material component A and a raw material component B;

[0008] The raw material component A includes: 55-65 parts of epoxy resin, 10-20 parts of modified filler, 1-5 parts of dihydroxy polydimethylsiloxane, 1-10 parts of auxiliary agent, and 30-50 parts of water;

[0009] Mixing epoxy resin, modified filler, dihydroxy polydimethylsiloxane, additives and water to obtain the raw material component A;

[0010] The B raw material component includes a curing agent;

[0011] Wherein, the preparation method of the modified filler comprises the following steps:

[0012] The modified filler is prepared by mixing nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and a solvent, and then adding sorbitol for stirring and dispersion.

[0013] The raw material components of the insulating paint of the present invention include raw material component A and raw material component B. When the insulating paint is used, raw material component A and raw material component B are mixed and cured to obtain a film layer. Among them, raw material component A is mainly composed of epoxy resin, and is matched with modified filler, dihydroxy polydimethylsiloxane, auxiliary agent, and water. The dihydroxy polydimethylsiloxane contains active hydroxyl groups, which can participate in the reaction during cross-linking and curing, and has a promoting effect on the formation of dense film. Moreover, the introduced siloxane structure is conducive to improving the water resistance of the insulating paint after film formation, so that the film layer still maintains a high breakdown strength even in a rainy environment. The modified filler is obtained by modifying nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent, and sorbitol. Using nano aluminum nitride, mica powder, and glass fiber as the main filler components helps to improve the insulation of the insulating paint, and is conducive to the uniformity of the dispersion of the modified filler in the epoxy resin. Sorbitol not only promotes the uniform dispersion of the main components of the filler, but also the chain and polyhydroxy characteristics of sorbitol enable the modified filler to participate in the curing cross-linking reaction, further allowing the components of the insulating paint to cross-link to form a more compact and uniform film layer. The film layer formed by the insulating paint has both high breakdown strength and good impact resistance.

[0014] Preferably, the preparation method of the modified filler comprises the following steps:

[0015] Nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and solvent are mixed, and then sorbitol is added and stirred and dispersed to obtain the modified filler; the weight ratio of the nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1: (0.1-1.5): (0.1-0.4): (0.1-0.8): (5-15): (0.2-1.0).

[0016] Preferably, the solvent includes water and may also include ethanol.

[0017] Preferably, the weight ratio of the raw material component A to the raw material component B is 10:(0.5-1.5), and more preferably 10:(0.6-1.2).

[0018] Preferably, the raw material component A includes: 55-58 parts of epoxy resin, 18-20 parts of modified filler, 2-5 parts of dihydroxy polydimethylsiloxane, 2-8 parts of auxiliary agent, and 30-40 parts of water.

[0019] Preferably, the epoxy resin is selected from at least one of bisphenol A epoxy resin and bisphenol F epoxy resin; further preferably, the epoxy resin is composed of bisphenol A epoxy resin and bisphenol F epoxy resin in a weight ratio of 1: (0.1-0.5). After the epoxy resin composed of this ratio is cross-linked and cured, the film layer formed has better density, which helps to improve the breakdown strength and impact strength of the film layer formed by the insulating paint.

[0020] Preferably, the auxiliary agent includes polydimethylsiloxane and / or nonylphenol polyglycol ether. Among them, polydimethylsiloxane not only has a defoaming effect, but also has a leveling effect. Nonylphenol polyglycol ether is a surfactant, which is beneficial to improve the uniformity of dispersion of each component, and when the insulating paint undergoes a curing reaction, since nonylphenol polyglycol ether contains hydroxyl groups, it can also undergo a cross-linking curing reaction, and introduce a nonylphenol structure into the film layer, which further significantly improves the density of the insulating paint after curing, which helps to improve the breakdown strength and impact strength of the film layer formed by the insulating paint.

[0021] Preferably, the auxiliary agent includes polydimethylsiloxane and nonylphenol polyglycol ether, and the weight ratio of polydimethylsiloxane to nonylphenol polyglycol ether is 1:(0.1-1.1), and more preferably 1:(0.5-0.8).

[0022] Preferably, the curing agent includes an imidazole curing agent and an isocyanate curing agent.

[0023] Preferably, the weight ratio of the imidazole curing agent to the isocyanate curing agent is 1:(0.3-1.1), and more preferably 1:(0.3-0.8).

[0024] Preferably, the imidazole curing agent is selected from at least one of 2-phenyl-4-methyl-5-hydroxymethylimidazole and 1-benzyl-2-methylimidazole.

[0025] Preferably, the isocyanate curing agent includes at least one of toluene diisocyanate and diisohexylmethane diisocyanate.

[0026] A second aspect of the present invention provides an application of a method for preparing an insulating varnish.

[0027] The invention discloses a method for preparing an insulating varnish and application of the insulating varnish prepared by the method in electrical equipment.

[0028] Preferably, the electrical equipment includes household appliances, high-voltage lines, transformers, etc.

[0029] When the insulating varnish is used, the raw material component A is first mixed with the raw material component B, coated on a substrate, and then kept at 60-100° C. for 0.5-1.5 hours, and then kept at 150-160° C. for 2-3 hours.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The insulating varnish of the present invention has a film layer having both high breakdown strength and good impact resistance by specifically selecting raw material components and modifying fillers, wherein the breakdown strength is not less than 161KV / mm and the impact resistance is not less than 85cm. DETAILED DESCRIPTION

[0032] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0033] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0034] A method for preparing an insulating varnish, comprising a raw material component A and a raw material component B;

[0035] A raw material component includes: 55-65 parts of epoxy resin, 10-20 parts of modified filler, 1-5 parts of dihydroxy polydimethylsiloxane, 1-10 parts of auxiliary agent, and 30-50 parts of water;

[0036] B raw material components include curing agent;

[0037] The preparation method of the modified filler comprises the following steps:

[0038] The modified filler is prepared by mixing nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and solvent, and then adding sorbitol for stirring and dispersion.

[0039] The preparation method of the modified filler comprises the following steps:

[0040] Nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and solvent are mixed, and then sorbitol is added and stirred and dispersed to obtain the modified filler; the weight ratio of the nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1: (0.1-1.5): (0.1-0.4): (0.1-0.8): (5-15): (0.2-1.0).

[0041] The solvent includes water and may also include ethanol.

[0042] The weight ratio of the A raw material component to the B raw material component is 10:(0.5-1.5), further 10:(0.6-1.2).

[0043] The raw material components A include: 55-58 parts of epoxy resin, 18-20 parts of modified filler, 2-5 parts of dihydroxy polydimethylsiloxane, 2-8 parts of auxiliary agent, and 30-40 parts of water.

[0044] The epoxy resin is selected from at least one of bisphenol A epoxy resin and bisphenol F epoxy resin; further, the epoxy resin is composed of bisphenol A epoxy resin and bisphenol F epoxy resin in a weight ratio of 1: (0.1-0.5). After the epoxy resin composed of this ratio is cross-linked and cured, the film layer formed has better density, which helps to improve the breakdown strength and impact strength of the film layer formed by the insulating paint.

[0045] The additives include polydimethylsiloxane and / or nonylphenol polyglycol ether. Among them, polydimethylsiloxane not only has a defoaming effect, but also has a leveling effect. Nonylphenol polyglycol ether is a surfactant, which is beneficial to improve the dispersion uniformity of each component, and when the insulating paint undergoes a curing reaction, since nonylphenol polyglycol ether contains hydroxyl groups, it can also undergo a cross-linking curing reaction, and introduce a nonylphenol structure into the film layer, which further significantly improves the density of the insulating paint after curing, which helps to improve the breakdown strength and impact strength of the film layer formed by the insulating paint.

[0046] The auxiliary agent comprises polydimethylsiloxane and nonylphenol polyglycol ether, and the weight ratio of polydimethylsiloxane to nonylphenol polyglycol ether is 1:(0.1-1.1), and further is 1:(0.5-0.8).

[0047] The curing agent includes imidazole curing agent and isocyanate curing agent.

[0048] The weight ratio of the imidazole curing agent to the isocyanate curing agent is 1:(0.3-1.1), and more preferably 1:(0.3-0.8).

[0049] The imidazole curing agent is selected from at least one of 2-phenyl-4-methyl-5-hydroxymethylimidazole and 1-benzyl-2-methylimidazole.

[0050] The isocyanate curing agent includes at least one of toluene diisocyanate and diisohexylmethane diisocyanate.

[0051] Application of the insulating varnish prepared by the above-mentioned method for preparing insulating varnish in electrical equipment.

[0052] Electrical equipment includes household appliances, high-voltage lines, transformers, etc.

[0053] When the insulating varnish is used, the raw material component A is first mixed with the raw material component B, coated on a substrate, and then kept at 60-100° C. for 0.5-1.5 hours, and then kept at 150-160° C. for 2-3 hours.

[0054] The substrate is metal, such as iron or aluminum.

[0055] The mica powder used in the following examples can pass through a 300-mesh sieve.

[0056] The diameter of the glass fiber is 2-5 μm and the length is 3-6 mm.

[0057] Example 1

[0058] A method for preparing an insulating varnish, comprising a raw material component A and a raw material component B;

[0059] A raw material component includes: 58 parts of epoxy resin (epoxy resin is composed of bisphenol A type epoxy resin), 18 parts of modified filler, 3 parts of dihydroxy polydimethylsiloxane, 6 parts of auxiliary agent (polydimethylsiloxane), and 40 parts of water;

[0060] Mixing the components of raw material component A to obtain raw material component A;

[0061] The raw material component B includes a curing agent, which is composed of 1-benzyl-2-methylimidazole and toluene diisocyanate in a weight ratio of 1:0.5;

[0062] The preparation method of the modified filler comprises the following steps:

[0063] Nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and water are mixed, and then sorbitol is added and stirred and dispersed to obtain a modified filler; the weight ratio of nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1:0.5:0.2:0.5:8:0.5.

[0064] The weight ratio of raw material component A to raw material component B is 10:0.8.

[0065] Example 2

[0066] A method for preparing an insulating varnish, comprising a raw material component A and a raw material component B;

[0067] A raw material component includes: 58 parts of epoxy resin (the epoxy resin is composed of 40 parts of bisphenol A epoxy resin and 18 parts of bisphenol F epoxy resin), 18 parts of modified filler, 3 parts of dihydroxy polydimethylsiloxane, 6 parts of auxiliary agent (polydimethylsiloxane), and 40 parts of water;

[0068] Mixing the components of raw material component A to obtain raw material component A;

[0069] The raw material component B includes a curing agent, which is composed of 1-benzyl-2-methylimidazole and toluene diisocyanate in a weight ratio of 1:0.5;

[0070] The preparation method of the modified filler comprises the following steps:

[0071] Nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and water are mixed, and then sorbitol is added and stirred and dispersed to obtain a modified filler; the weight ratio of nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1:0.5:0.2:0.5:8:0.5.

[0072] The weight ratio of raw material component A to raw material component B is 10:0.8.

[0073] Example 3

[0074] A method for preparing an insulating varnish, comprising a raw material component A and a raw material component B;

[0075] A raw material component includes: 58 parts of epoxy resin (the epoxy resin is composed of 40 parts of bisphenol A epoxy resin and 18 parts of bisphenol F epoxy resin), 18 parts of modified filler, 3 parts of dihydroxy polydimethylsiloxane, 6 parts of auxiliary agent (the auxiliary agent is composed of polydimethylsiloxane and nonylphenol polyglycol ether, and the weight ratio of polydimethylsiloxane to nonylphenol polyglycol ether is 1:0.8), and 40 parts of water;

[0076] Mixing the components of raw material component A to obtain raw material component A;

[0077] The raw material component B includes a curing agent, which is composed of 1-benzyl-2-methylimidazole and toluene diisocyanate in a weight ratio of 1:0.5;

[0078] The preparation method of the modified filler comprises the following steps:

[0079] Nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and water are mixed, and then sorbitol is added and stirred and dispersed to obtain a modified filler; the weight ratio of nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1:0.5:0.2:0.5:8:0.5.

[0080] The weight ratio of raw material component A to raw material component B is 10:0.8.

[0081] Example 4

[0082] A method for preparing an insulating varnish, comprising a raw material component A and a raw material component B;

[0083] A raw material component includes: 62 parts of epoxy resin (the epoxy resin is composed of 50 parts of bisphenol A epoxy resin and 12 parts of bisphenol F epoxy resin), 20 parts of modified filler, 4 parts of dihydroxy polydimethylsiloxane, 7 parts of auxiliary agent (polydimethylsiloxane), and 40 parts of water;

[0084] Mixing the components of raw material component A to obtain raw material component A;

[0085] The raw material component B includes a curing agent, which is composed of 2-phenyl-4-methyl-5-hydroxymethylimidazole and toluene diisocyanate in a weight ratio of 1:0.7;

[0086] The preparation method of the modified filler comprises the following steps:

[0087] Nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and water are mixed, and then sorbitol is added and stirred and dispersed to obtain a modified filler; the weight ratio of nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1:1.1:0.1:0.6:10:0.8.

[0088] Comparative Example 1

[0089] Compared with Example 1, the difference of Comparative Example 1 is that an equal amount of polydimethylsiloxane is used to replace the dihydroxy polydimethylsiloxane in Example 1, and other components and processes are the same as those in Example 1.

[0090] Comparative Example 2

[0091] Compared with Example 1, the difference of Comparative Example 2 is that the sorbitol in Example 1 is replaced by an equal amount of ethylene glycol, and the other components and processes are the same as those in Example 1.

[0092] Comparative Example 3

[0093] Compared with Example 1, the difference of Comparative Example 3 is that the mica powder in Example 1 is replaced by an equal amount of nano hexagonal boron nitride, and the other components and processes are the same as those in Example 1.

[0094] Product effect testing

[0095] Take equal amounts of the insulating varnishes prepared in the above-mentioned embodiments and comparative examples, mix the raw material component A and the raw material component B evenly, then apply them on a tinplate substrate, and then keep them warm at 90°C for 1 hour and then keep them warm at 160°C for 2.5 hours to obtain a film layer formed by the insulating varnish corresponding to the embodiment and the comparative example, and then test the breakdown strength of the film layer according to GB / T1981.2-2009 and the impact strength of the film layer according to GB / T1732-1993. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] It can be seen from Table 1 that the breakdown strength and impact strength of the film layers formed by the insulating varnishes prepared in Examples 1-4 are significantly better than those in Comparative Examples 1-3.

[0099] It can be seen from Example 1 and Comparative Example 1 that Comparative Example 1 does not use hydroxypolydimethylsiloxane, which makes it difficult for the polydimethylsiloxane in Comparative Example 1 to participate in the cross-linking reaction and the siloxane cannot be evenly introduced, further weakening the water resistance of the film layer formed by the insulating paint, resulting in a significant decrease in the breakdown strength of the film layer corresponding to Comparative Example 1 after immersion in water for 24 hours.

[0100] Comparative Example 2 uses ethylene glycol instead of sorbitol in Example 1, which results in poor dispersion uniformity of the components, resulting in decreased breakdown strength and impact resistance of the film layer.

[0101] In Comparative Example 3, the type of filler is changed, so that the breakdown strength of the film layer decreases.

[0102] It can be seen from Comparative Examples 1-3 and Example 1 that the present invention has selectivity for the raw material components for preparing the insulating varnish.

Claims

1. A method for preparing an insulating varnish, characterized in that: It includes A raw material component and B raw material component; The raw material component A includes: 55-65 parts of epoxy resin, 10-20 parts of modified filler, 1-5 parts of dihydroxy polydimethylsiloxane, 1-10 parts of auxiliary agent, and 30-50 parts of water; The epoxy resin, modified filler, dihydroxy polydimethylsiloxane, additives and water are mixed to obtain the A raw material component; The B raw material component includes a curing agent; Wherein, the preparation method of the modified filler comprises the following steps: Mixing nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate and solvent, then adding sorbitol and stirring and dispersing to obtain the modified filler; The weight ratio of the nano aluminum nitride, mica powder, glass fiber, sodium dodecylbenzene sulfonate, solvent and sorbitol is 1: (0.1-1.5): (0.1-0.4): (0.1-0.8): (5-15): (0.2-1.0); The weight ratio of the raw material component A to the raw material component B is 10:(0.5-1.5).

2. The preparation method according to claim 1, characterized in that: The raw material component A comprises: 55-58 parts of epoxy resin, 18-20 parts of modified filler, 2-5 parts of dihydroxy polydimethylsiloxane, 2-8 parts of auxiliary agent and 30-40 parts of water.

3. The preparation method according to claim 1, characterized in that: The epoxy resin is selected from at least one of bisphenol A epoxy resin and bisphenol F epoxy resin.

4. The preparation method according to claim 1, characterized in that: The auxiliary agent includes polydimethylsiloxane and / or nonylphenol polyglycol ether.

5. The preparation method according to claim 4, characterized in that: The auxiliary agent comprises polydimethylsiloxane and nonylphenol polyglycol ether, and the weight ratio of polydimethylsiloxane to nonylphenol polyglycol ether is 1:(0.1-1.1).

6. The preparation method according to any one of claims 1 to 5, characterized in that: The curing agent includes an imidazole curing agent and an isocyanate curing agent.

7. The preparation method according to claim 6, characterized in that: The imidazole curing agent is selected from at least one of 2-phenyl-4-methyl-5-hydroxymethylimidazole and 1-benzyl-2-methylimidazole; and / or the isocyanate curing agent includes at least one of toluene diisocyanate and diisohexylmethane diisocyanate.

8. Use of the insulating varnish prepared by the preparation method according to any one of claims 1 to 7 in electrical equipment.

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